<!-- TETRAGONAL P4 SPACE GROUPS -->
<input type="checkbox" name="spacegroups[]" id="sg_P4" value="P4"> P4<br/>
<input type="checkbox" name="spacegroups[]" id="sg_P41" value="P41"> P41<br/>
<input type="checkbox" name="spacegroups[]" id="sg_P42" value="P42"> P42<br/>
<input type="checkbox" name="spacegroups[]" id="sg_P43" value="P43"> P43<br/>